In vitro and in silico investigation of the critical role of GABAB receptor activation in human breast cancer and its natural agonistsIn vitro and in silico investigation of the critical role of GABAB receptor activation in human breast cancer and its natural agonists.

γ-aminobutyric acid type B (GABAB) receptors, a class of G protein-coupled receptors, serve pivotal roles in modulating cellular signaling pathways across both neural and peripheral tissues, although their underlying mechanisms involved in cancer progression have yet to be fully elucidated. The aim of the present study was to investigate the effect of GABAB receptor activation on the migration, invasion, clonogenicity, proliferation and epithelial-mesenchymal transition (EMT) of the MDA-MB-231 human breast cancer cell line. To meet this aim, MDA-MB-231 cells were treated with various concentrations of the GABAB receptor agonist, baclofen. Treatment with baclofen caused a significant inhibition of cell migration, invasion and clonogenicity in a dose-dependent manner. Moreover, baclofen treatment led to a downregulation of vimentin expression, whereas the expression of β-catenin was upregulated, indicating suppression of EMT in MDA-MB-231 cells. Notably, the phosphorylation levels of Akt and ERK1/2 remained unaltered, suggesting that the inhibitory effects mediated by baclofen on EMT were not mediated via either the phosphoinositide 3-kinase/Akt or the MAPK pathways. To identify potential natural GABAB receptor agonists, molecular docking techniques were employed using the MPD3 database. This in silico approach revealed three compounds (PubChem identification, 450432, 6448 and 6057) as promising candidates, which all exhibited critical hydrogenbond interactions with the GABAB receptorbinding site. These compounds may serve as lead compounds for developing novel, naturally derived GABAB receptor agonists. Taken together, the findings demonstrated that GABAB receptor activation via baclofen inhibits multiple aggressive phenotypes in MDA-MB-231 breast cancer cells. Moreover, these results offer promising avenues for developing GABAB receptor agonists as a therapeutic strategy in breast cancer treatment.